Вычислите По Действиям:
в) (2/5 - 2/7) : 2/7 * 2/5 =
г) (5/6 - 3/10) : (3/10 + 2/15) =

$frac{2}{5} - frac{2}{7}= frac{14}{35}- frac{10}{35}= frac{4}{35}$
$frac{4}{35}: frac{2}{7}= frac{4}{35}* frac{7}{2}= frac{2}{5}$
$frac{2}{5}* frac{2}{5}= frac{4}{25}$
$frac{5}{6}- frac{3}{10}= frac{50}{60}- frac{18}{60}= frac{32}{60}= frac{8}{15}$
$frac{3}{10} + frac{2}{15}= frac{9}{30}+ frac{4}{30}= frac{13}{30}$
$frac{8}{15}: frac{13}{30}= frac{8}{15}* frac{30}{13} =frac{16}{13}=1 frac{3}{13}$